Researchers have identified a genetic factor that may
predispose young people to harmful drinking habits. A team
of scientists interviewed college students about their
alcohol consumption and then analyzed their genetic
profiles, or genotypes. They found that students who shared
a particular variant of the serotonin transporter gene
(5HTT) consumed more alcohol per occasion, more often drank
expressly to become inebriated, and were more likely to
engage in binge drinking than students without the variant.
The study appears in the current issue of the journal
"Alcohol and Alcoholism".

"This research provides important new evidence that the
risk of developing a maladaptive pattern of alcohol
consumption is influenced by genetically determined
neurobiological differences that exert their effects during
young adulthood," says Ting-Kai Li, M.D., director of the
National Institute on Alcohol Abuse and Alcoholism (NIAAA).

NIAAA clinical investigators Paolo B. DePetrillo, M.D., and
Research Fellow Aryeh I. Herman B.A., along with
researchers from George Washington University in
Washington, D.C., conducted the study of 262 male and
female college students and analyzed data from the largest
homogenous group: 204 male and female Caucasian college
students aged 17 to 23 years. To assess the frequency and
patterns of alcohol consumption, the scientists asked all
the students a set of questions, for example, how many
times in the past two weeks they had engaged in binge
drinking (five or more drinks for men and four or more
drinks for women on one occasion).

The research team also analyzed each student's genotype
with a focus on the 5-HTT gene, which is involved in
recycling the chemical serotonin after it is secreted into
the synapse of a cell. The researchers determined which
students had long or short versions of this so-called
serotonin transporter gene.

Everyone inherits two copies of each gene, one from each
parent. There are two normal variations, or polymorphisms,
of the serotonin transporter gene, labeled the long and the
short variants. Most people are heterozygous, that is, they
have one copy of each variant, but about 30 percent of the
Caucasian population are homozygous (carry duplicate
copies) of either the long or the short version. This
percentage varies depending on the ethnic background of the
individual.

The researchers found that the students who carried two
copies of the short version of 5-HTT were more likely to
report troublesome drinking patterns. Dr. DePetrillo says,
"Our findings reveal a significant association of the
serotonin transporter promoter polymorphism with increased
alcohol consumption behavior in the students that we
studied. Taken together with other research, this finding
suggests that genetically mediated differences in
serotonergic response play an important role in mediating
patterns of alcohol intake." The students with two copies
of the short form of the gene engaged more frequently in
binge drinking, drank more often to get drunk, and consumed
more alcoholic drinks per occasion than did students with
the other genotypes.

Another difference the researchers observed was that
students with at least one copy of the long variant of the
5-HTT gene tended to consume a smaller number of drinks at
a sitting, even though they went out to drink as often as
the other students.

Why should the presence of the shorter gene variant make
such a difference? The authors speculate that, because
individuals who are homozygous for the short version are
known to be at risk for higher levels of anxiety, they may
use alcohol to reduce tension. Further studies are needed
to understand the influence of the serotonin transporter
gene on drinking behavior, with special attention given to
replication in other ethnic groups.

The article "Serotonin transporter promoter polymorphism
and differences in alcohol consumption behavior in a
college student population" is published as a Rapid
Communication at . The
study will appear in the September printed issue of
"Alcohol and Alcoholism" (Volume 38, Number 5).

Additional information about genetic and
other areas of NIAAA research is available from the NIAAA
Press Office and at .

The National Institute on Alcohol Abuse and Alcoholism, a
component of the National Institutes of Health, U.S.
Department of Health and Human Services, conducts and
supports approximately 90 percent of U.S. research on the
causes, consequences, prevention, and treatment of alcohol
abuse, alcoholism, and alcohol problems and disseminates
research findings to science, practitioner, policy making
and general audiences.

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